I'm currently in the process of designing a VV mod around the 10A naos raptor module with a battery protection chip and a charger built into it. I'm trying to build a mod that is a cost effective solution for most people and will have some boards made up if anybody wants one when i'm finished. I'm still working on the schematic for it but would like some help to add accurate ohms reading. I will post my schematic when i get it finished and any feedback is appreciated. Also if somebody would like to work along side me designing it that would be great as I'm not the greatest electrical engineer.
Designing a VV mod and would like some help
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Just a suggestion, but have you looked into the Murata OKL2 series? They have a tracking input that you could feed with an analog voltage and are surface mount sub assemblies that you could reflow direct to your board. Course you would be limited to your DAC max voltage unless you included an opamp or similar way to translate voltage.
I just chose the raptor module because it's what i had on hand and they're easy to find. The SI9730 is a battery protection chip with over volt, under volt, and current protection. U1 is the charger ic in my circuit. I did think about using a dac to sent an analog voltage to the trim pin but got side tracked when trying to find a digital potentiometer for it which are hard to find in low resistances.
For determining the resistance of the coil you need to measure the voltage across the coil and the current flowing through it (V=IR). You can probably rig up something using some resistors, a couple of opamps and one of the 328's ADC channels, or you can investigate the easy option...
www.ti.com/lit/ds/symlink/ina219.pdf
it's good reading and while this part may be overkill the first page of the datasheet links to a few alternative parts and I'm sure options are available from other manufacturers.
For changing the output voltage, the Naos Raptor datasheet shows a trim resistor between pin 5 and ground. I'm no expert but it may be possible to connect the resistor between pin 5 and the output of an opamp (*instead of ground) then drive the input of the opamp with a filtered PWM signal. With a little experimentation the 328 should be able to drive the op voltage to whatever you desire... Read the op voltage back via the ina219 or a separate resistor divider + opamp + ADC input.
*instead of ground: The opamp output is acting as a virtual ground, by changing this you fool the Naos into seeing what would be different resistances with respect to actual ground. Make sure to use an opamp that is capable of driving its output close to ground, how close? Close enough to work
www.ti.com/lit/ds/symlink/ina219.pdf
it's good reading and while this part may be overkill the first page of the datasheet links to a few alternative parts and I'm sure options are available from other manufacturers.
For changing the output voltage, the Naos Raptor datasheet shows a trim resistor between pin 5 and ground. I'm no expert but it may be possible to connect the resistor between pin 5 and the output of an opamp (*instead of ground) then drive the input of the opamp with a filtered PWM signal. With a little experimentation the 328 should be able to drive the op voltage to whatever you desire... Read the op voltage back via the ina219 or a separate resistor divider + opamp + ADC input.
*instead of ground: The opamp output is acting as a virtual ground, by changing this you fool the Naos into seeing what would be different resistances with respect to actual ground. Make sure to use an opamp that is capable of driving its output close to ground, how close? Close enough to work
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A whole mod or just a control head for a mech mod?
A control head that goes on a mech would be nice;
but it need to work in mostly-off mode; meaning it's only going to get power when you press the button on the mech side;
so instead of pushbuttons for settings, it might be better to have rotation wheel type settings/modes; and it can't take 2 to 5 seconds to power up, it would have to activate instantly upon application of power.
A control head that goes on a mech would be nice;
but it need to work in mostly-off mode; meaning it's only going to get power when you press the button on the mech side;
so instead of pushbuttons for settings, it might be better to have rotation wheel type settings/modes; and it can't take 2 to 5 seconds to power up, it would have to activate instantly upon application of power.
I've been thinking on this all day and I think I can use a current sensor like the acs715 to measure the current and the atmega to measure voltage and calculate the resistance from that. I tried using a constant current source to measure it but using low current didn't give very consistent results for me. It might be my power supply I'm using. I haven't experimented with the raptor module yet as I've been enjoying it as a pass through instead so I'd guess I'll have to look into using an opamp but it's a pain to get a reliable filtered signal from the PWM and it would have to be isolated well with the switching frequency of the regulator or it could cause problems with the opamp possibly. The other thing that may work is using a DAC to set the ground reference.
I did think of using a rotary encoder for the menu and adjustment options. It wouldn't be difficult to add that into it instead of buttons and I may do just that but I haven't decided yet. I never thought about making a control head for a mech though. I'd guess if you leave the battery protection ic and charger off it might be small enough for a control head but without the right enclosure it would look odd sitting on top of a mech.
Thanks for the feedback. I enjoy making circuit boards but I suck at designing them as I'm only self taught in electronics so my knowledge is limited.
I did think of using a rotary encoder for the menu and adjustment options. It wouldn't be difficult to add that into it instead of buttons and I may do just that but I haven't decided yet. I never thought about making a control head for a mech though. I'd guess if you leave the battery protection ic and charger off it might be small enough for a control head but without the right enclosure it would look odd sitting on top of a mech.
Thanks for the feedback. I enjoy making circuit boards but I suck at designing them as I'm only self taught in electronics so my knowledge is limited.
lightningvapes sells this little gizmo for $13; you screw it on your mech, and you screw your tank on it.
It shows volts when you fire the mech;
Now if you had a rotary switch or two on it instead of only showing volts you could optionally show ohms, and/or switch to the vv module to kick the voltage output.
That way, a vaper can afford to buy a simple mech to start with, then later on buy the control head; later on maybe they upgrage the mech
I thought some more now that I got some sleep and I don't think this circuit would work for a control head because the min voltage for this module is 4.5V according to the datasheet. So in order to use it you'd have to stack batteries to get the voltage above the min voltage for the buck converter and I think a simpler circuit would be better. It wouldn't be hard to put together with a digital potentiometer that has a up/down button interface and have the voltage mod display the current output voltage but I don't like the idea of using stacked batteries without battery protection so I'd recommend protected batteries in that case if you can find them with a 10 amp limit.
How about you forget about batteries and aim to use it on a 5 volt USB plugin port!
This module isn't designed for a usb port. in order to get 5V output you'd need over 7V into it and I wouldn't want to try to drain 10 amps from my usb port lol. I have a passthrough for my computer and it doesn't work as well as I'd like because of the current limit from my computer's usb port. You could use this module without the battery protection and charger chips if you have a 9-10V adapter that can supply 10A of current though. That's how I'm testing the module out now is by running it off of a 10V 30A PSU but with a little change in the circuit you could use it off of an old computer PSU for example if you use the 12V line on it.
Everybody has cellphones nowadays and they all charge off usb power;
usb wall warts are becoming more and more common; below is a 15 watt one.
All you need to vape is 5 watts so up to 10 watts is quite suitable and 15 is nice and covers most applications
A module that runs of 12 volts is sensible; you can use it on the car; but a module that runs on 5 volts usb would have a vastly wider application because of the millions of usb ports out there.
The standard usb port I believe is 1 amp limit; so that's 5 watts, and that'll do; if you need more power you get a 10+ watt wall wart.
usb wall warts are becoming more and more common; below is a 15 watt one.
All you need to vape is 5 watts so up to 10 watts is quite suitable and 15 is nice and covers most applications
A module that runs of 12 volts is sensible; you can use it on the car; but a module that runs on 5 volts usb would have a vastly wider application because of the millions of usb ports out there.
The standard usb port I believe is 1 amp limit; so that's 5 watts, and that'll do; if you need more power you get a 10+ watt wall wart.
You could use a usb port for 5 watts multiplied by the efficiency of the converter for about 4.75 watts of power to the atomizer but I think most people vape higher than that. Even 10 watts is a little low for myself since I vape 20 watts for a dual coil which is why I'm building this although the max capacity of the buck converter I chose is 50 watts. It would be fairly simple to make a simpler circuit to vape off of the adapter you posted for 14.25 watts to your atomizer (5 volts * 3 amps * 95% efficiency = 14.25 watts of power). I personally don't have any interest in making this into a dedicated passthrough as I need something portable but could probably put a schematic together for one after I'm done with this if there's interest in a lower power dedicated passthrough so people wouldn't have to use a battery powered device when there's an electrical outlet sitting right next to them.
Hey, did you know that provape makes a 12v 18650 sized passthrough module that you slide into the tube instead of a battery?
Never saw that before. Not much on specs from their website on it as far as current and voltage but it's probably 4.2V and capable of 4 amps or so. Nice idea it just sucks that it's only for the provari and the fact that they used a RCA phono connector instead of a locking connector of some sort but I suppose the phono connector does make it easier to find extensions and such for it. I'd buy it if I had a provari.
I figure it should work on a sigelei zmax; should be the same thread.
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